Monday, October 08, 2007
Code Coverage Subtleties
Posted on Monday, October 08, 2007 6:38:29 PM (Mountain Daylight Time, UTC-06:00)  Comments [2] | 
Categories: ArcGIS Devt | Unit Testing

I wanted to raise the coverage numbers noted in my last posting, so I jumped onto the code, looked at the coverage, and realized that I needed another test. I added this is, and my coverage jumped from 35% to ~70%. Good I thought - and went to look at the coverage output to see what other corner case I had not covered.

What I saw was very interesting. All the code was highlighted  as being run. Wha?

The SecurityManager.CanUserEditObject method basically does 3 levels of security checks - it checks the layer's "default policy", a layer-wide editor role, and finally a per-user, per-feature policy. Thus, the code is structured around 3 nested select blocks... (simplified example below)

            Select Case GetDefautlPolicy(obj)

                Case AccessGranted

                    Return True

                Case AccessDenied

                    Select Case CheckRolePolicy(obj)

                        Case AccessGranted

                            Return True

                        Case AccessDenied

                            Select Case CheckUserPolicy(obj)

                                Case AccessGranted

                                    Return True

                                Case Access Denied

                                    Return False

                            End Select

                    End Select

            End Select

 

What was interesting was that by directly returning from inside the case statements was causing the code coverage numbers to be lower than you would expect. Since this is a bit of a code-smell, I refactored the code to only have one return statement at the end. That alone got me 10% more coverage - no more actual code was run, but the coverage algorithm liked it better. Below is an image of the code-coverage highlighting.

 

code-coverage

Even at this point, the Visual Studio code coverage tool is reporting only 87.5% coverage for this block.

Anyhow - the take home here is that the code coverage algorithms are fickle, and even though you tests hit all the code, you may not get 100%.

Thursday, October 11, 2007 5:13:49 PM (Mountain Daylight Time, UTC-06:00)
Have you tried NCover?
Rich Ruh
Thursday, October 11, 2007 7:14:45 PM (Mountain Daylight Time, UTC-06:00)
Rich,

I was doing this testing @ work, and we're using the Microsoft Tooling there. I have used NCover in some other stuff I've done, and while I have not run this exact code through it, I have not seen this same behavior.

Cheers,

Dave
Dave
Comments are closed.